Kiln



Oct. 17, 1944. A. J. RUCKMAN KILN Filed May 12, 1941 2 Sheets-Sheet l Oct. 17, 1944.

A. J; RUCKMAN KILN Filed May 12, 1941 2 Sheets-Sheet 2 Patented Oct. 17, 1944 UNITED STATES PATENT OFFICE;

KI N

Albert J. Ruckman, Mayville, N. Y. Application May 12, 1941, Serial No. 393,008

6 Claims.

This invention relates to dry kilns and more particularly to structural improvements by which to increase the efiiciency thereof.

In its present form the invention is directed to the structure of a kiln for drying quantities of lumber. 'It is the general practice to provide a kiln structure of a size to accommodate several small lumber'filled cars or trucks. These cars are preferably track-mounted and enter and leave the kiln through suitable doors located in an end or side of the structure.

In the building and furniture trades it is generally required and certainly desirable that lumber be kiln dried. Due to the fact that the initial cost of manufacture of kilns is high and that they must be properly constructed and operated to obtain satisfactory results, they are generally of moderate size and can accommodate only a few thousand feet of lumber'at a time. The process of drying lumber is somewhat lengthy as it has not been found possible to rapidly remove moisture without causing undesirable physical changes in the lumber being dried. Increased demand of the public from the building and furniture trades frequently causes a shortage of kiln dried lumber. As the lumber can be dried only so fast, it would appear that building and furniture manufacturers are limited in their production and that lumber drying, in a sense, constitutes'a bottle-neck in these trades whenever unforeseen public demand occurs. As already mentioned, drying kilns are costly to erect and maintain and, therefore, the building of additional kilns to handle intermittent'or occasional increased lumber demands is not practical.

It is the purpose and principal object of the present invention to provide a structure for drying kilns that greatly decreases the jdrying'time of lumber, and by reason of which it is believed the above enumerated difliculties may be overcome.

Another object of the invention lies in the provision of a drying kiln,-the structure'of which is applicable to old and new kilns alike for the purpose of speeding upthe process of drying lumber.

Another object of the invention lies in the provision of a drying kiln, the structure of which includes circulation ducts, so arranged and proportioned that the drying air is uniformly effec-' tive in all parts of the kiln. Another object of the invention lies in the provision of a drying kiln in which fresh air is caused to enter the kiln to the same extent that excessively moist or foul air isremoved.

Another object of the invention lies in the provision of a drying kiln of comparatively inexpensive structure, readily installable and easily maintained.

Other objects and advantages of the invention will be more fully understood from a consideration of the following specification, taken in conjunction with the accompanying drawings; and in which Figure 1 is a vertical transverse'sectional view of a' structure embodying one form of the invention, being taken substantially on the line I--I of Figure 2;

Figure 2 is a fragmentary horizontal sectional 7 view, taken substantially on the line 22 of Fig view, taken substantially on the line 44 of Fig- I ure 1; and

Figure 5 is a fragmentary vertical sectional View, taken substantially on the line 55 of Fig} ure 1.

Reference is now had to the drawings wherein the numeral I0 is employed to generally designate a kiln embodying one form of the invention. The kiln, in its present form, includes a foundation II that may be below ground. This foundation comprises upstanding end and side walls I2 and I3, respectively, together'with a base wall Id. Suitable posts or columns I6 are set on the base I i, preferably over reinforced portions I'I. These columns support transversely disposed I-beams, the ends of which are carried by and secured to the side walls I3 in any Well known manner. Arranged lengthwise of the kiln and supported on the I-beams I8 is a slat flooring I9. Pairs of tracks 2I are also carried by the beams I8 and support and guide lumber laden trucks into and out of the kiln. In the middle of one of the end walls I2 is a fresh air inlet duct 22. This duct (see Figure 3) opens to the outside of the kiln somewhat above the foundation wall I3 and extends downwardly of the inside of this wall, thence across the base the upper portion of the kiln, the fourth side being fitted with conventional swinging or sliding doors, as found most suitable. A roof 26 is applied to the walls 24 and 25 and cooperates therewith to complete the enclosure. The roof structure is neither described nor shown in detail inasmuch as it may be of any suitable heat insulated construction and forms no part of the present invention. Beneath the roof 26 and spaced therefrom by supports 2'! is a ceiling plate 28.

From an examination of Figures 2 and 4 of the drawings, it is evident that a number of studs or uprights are applied to the side walls 25. These uprights, in part, define air circulation and exhaust ducts. In the present disclosure an upright 29 is located between an end wall 24 of the kiln and a pair of spaced uprights 3|). The,

uprights 29 extend from the base wall M to the ceiling plate 28, whereas uprights 30 commence several inches above the base wall I4 and extend through the ceiling plate 28 and roof 26. This arrangement of uprights is adhered to at both ends of each of the side walls 25. Between the pairs of uprights 30 described is at least one additional pair of uprights 30 and additional uprights 29 are interposed between these pairs, the number depending somewhat on the length of the kiln, together with the desired spacing. For a clearer understanding of the invention, the end wall and adjacent upright 29 form air circulation ducts 3|. Ducts 32 are located one on each side of a pair of uprights 30. As mentioned, there are additional ducts 3| defined -by uprights 29 between pairs of uprights 38. Ducts 33 are of the nature of foul air exhaust stacks and project above the roof 26, as at 34, being fitted with suitable caps 35.

Mounted on the base wall l4 are partition members 36 that correspond in number and position to the uprights 29 and 3D. The partition members (see Figures 1 and 2) at one end stop short of the center of the kiln and at the other end abut uprights 29 and 30. Further partition members 3'! are secured to the ceiling plate 28 and these members also correspond in number and position to the uprights 29 and 39. The members 31, while the same length as the members 36, are somewhat tapered, substantially as shown in the drawings. Suitable covering 38 is applied to the edges of uprights 29 and 30 and forms the fourth or enclosing wall of the ducts 3|, 32, and stacks 33. The covering 38, insofar as ducts 3| are concerned, extends from members 36 to members 31, but extends to the base wall I4 and ceiling plate 28 between pairs of those partition members 36 and 31 that correspond to pairs of uprights 36. Thus, stacks 33 are not directly open to the interior of the kiln as are ducts 3| and 32. A suitable flooring 43 is applied to the members 36 and extends from front to rear of the kiln. A slot 44 is made in the flooring for a purpose hereinafter more fully set forth. A covering 46 is applied to the members 3'! and partakes of the nature of a sub-ceiling. This covering is formed with an interrupted slot 48 corresponding in position and width to the slot 44 of the flooring 43. From the foregoing it will be noted that there are bottom horizontal extensions 3|a and 32a to the ducts 3| and 32 and also top horizontal extensions SH) and 32b to the ducts 3| and 32.

Beneath the I-beams I8 is located a suitable heating unit, indicated by the numeral 49. The size and arrangement of the heating unit is generally dependent on the size of the kiln, of any of several well known types, and forms no part of the invention.

Operation of the device is as follows: It is assumed that one or more cars or trucks of lumber have been moved into the kiln over tracks 2|, the kiln doors closed, and the heating unit 49 turned on. As air about the unit becomes heated, it rises through the apertures of the floor l9, passing around and through the lumber on the cars or trucks. In so doing a certain amount of moisture from the lumber is taken on by the air and carried upwardly toward the ceiling of the kiln. The air moves into contact with the covering 46, some of it passing through the open ends of ducts 3|b and 32b, slots 48, and additional slots 480.. This air is forced downwardly of the ducts 3| and 32 by reason of the continued rising of air heated by the unit 49. The air from ducts 3| passes into the extensions 3|a thereof, into the bottom of the kiln, part of it through apertures 50, slot 44, and the open ends of the extensions 3|a. The air passing downwardly of ducts 32 in part returns to the bottom of the kiln and in part by-passes upwardly of the stacks 33. Assuming the kiln to be sealed against undesired heat losses, only the same amount of air may pass out of the stacks 33 as is permitted to enter through the inlet duct 22, and since there is but one inlet duct, it is evident that the arrangement and number of stacks 33 are for the purpose of removal of foul or moisture laden air uniformly from all parts of the kiln. It is contemplated that the outside aperture of the inlet duct 22 or the size of the slots 23 therein may be made variable for the purpose of controlling the fresh air exchange in the kiln during the drying operation. As air continues to circulate in the manner above described, moisture taken from the lumber is exhausted and replaced by fresh air having a considerably less moisture content. It is to be particularly noted that the duct extensions 3|a and 3|b, together with the apertures therein, serve to prevent eddy currents within the kiln proper.

From the foregoing it is evident that applicant has produced a kiln having ducts and stacks of an arrangement such that there is a slow and constant removal of foul. or moisture laden air and replacement by fresh air and that this circulation is obtainable in all parts of the kiln without resort to forced draft devices, and although applicant has shown and described only one form of the invention, it will be apparent to those skilled in the art that variations and modifications may be made and are contemplated insofar as they are within the spirit and scope of the invention as set forth in the annexed claims.

Having thus set forth my invention what I claim as new and for which I desire protection by Letters Patent is:

1. In a drying kiln having a walled enclosure, and material supporting means, a heating unit beneath said material supporting means, an air inlet duct disposed centrally of and extending substantially the full length of said enclosure, said inlet duct having openings of predetermined arrangement and size, a set of. air circulation ducts in each side wall of said enclosure, the lower ends of the ducts of each set extending horizontally beneath said heating unit and terminating adjacent said inlet duct, the upper ends of the ducts of each set extending along the ceiling of said enclosure and having the same horizontal disposition as the lower ends thereof.

2. A drying kiln comprising a walled enclosure, material supporting means in said enclosure, a heating unit beneath said material supporting means, an air inlet duct disposed centrally of and extending substantially the full length of said enclosure, said inlet duct having openings of predetermined arrangement and size, a set of air circulation ducts in each side wall of said enclosure, the lower ends of the ducts of each set extending horizontally beneath said heating unit and terminating adjacent said inlet duct, the upper ends of the ducts of each set extending along the ceiling of said enclosure and having the same horizontal disposition as the lower ends thereof, and exhaust stacks interposed between and opening into certain of the air circulation ducts of each side wall, said stacks serving to pass foul and moisture laden air from the interior to the exterior of said kiln.

3. In a drying kiln having walls forming a substantially air tight enclosure, a plurality of air circulation ducts in opposite walls of said kiln, each of said ducts having top and bottom horizontally disposed continuations thereof, the continuations of the duo-ts of one wall being opposed to those of the other wall and all of said continuations stopping short of the longitudinal center of said kiln, said continuations having correspondingly disposed apertures effective to eliminate eddy currents during circulation of air in said kiln.

4. In a drying kiln having walls forming a substantially air tight enclosure, means in said kiln for supporting material to be dried, a heating unit beneath said material supporting means, said supporting means and said heating unit being positioned a substantial distance above the base of said kiln, a plurality of ducts arranged transversely of the interior of said kiln and disposed in opposed sets, the ducts of each of said sets comprising substantially horizontal top and bottom portions connected by vertical portions, and air inlet and exhaust means providing continuous change of air in said kiln without disturbing the functioning of said air circulation ducts.

5. In a drying kiln having walls forming a substantially air tight enclosure, and a heating unit therefor, a plurality of air circulation ducts in opposite walls of said kiln, each of said ducts having top and bottom horizontally disposed continuations thereof, the continuations of the ducts of one wall being opposed to those of the,

other wall, and all of said continuations termi-. nating near the longitudinal center of said kiln, said continuations being suitably apertured to facilitate air entering and leaving said ducts at a rate to circulate air heated by said unit, an air inlet duct cooperating with the bottom continuations of the air circulation ducts and air exhaust stacks cooperating with certain of said air ducts to remove foul and moisture laden air from said kiln.

6. In a drying kiln having walls forming a substantially air tight enclosure, a plurality of air circulation ducts in opposite walls of said kiln, each of said ducts having top and bottom substantially horizontally disposed continuations thereof, the continuations of the ducts of one wall being opposed to those of the other wall and all of said continuations stopping short of the center of said kiln, means in the kiln for supporting material to be dried and a heating unit beneath said material supporting means, said top and bottom continuations being located respectively above and beneath the heating unit and material supporting means.

ALBERT J. RUCKMAN. 

